Electrical switches with plural breaks



Oct. 14, 1969 .1. E. SORENG ETAL ELECTRICAL SWITCHES WITH PLURAL BREAKS2 Sheets-Sheet 1 FIG. 2

Filed May 29, 1967 FIG.

I N Vf N TORS John E. Sor

Oct. 14,1969 ESQRENG ETAL 3,472,975 I ELECTRICAL SWITCHES WITH PLURALBREAKS Filed May 29, 1967 C 2 Sheets-Sheet 2 I FIG. 3 F

x 36 2a 4 2 32 3 G J United States Patent ELECTRICAL SWITCHES WITHPLURAL BREAKS John E. Soreng, Eugene, Greg, and Jesse M. Cobb, Glenview,Ill., assignors to Inrlak Manufacturing Corp.,

Northbrook, 11]., a corporation of Illinois Filed May 29, 1967, Ser. No.641,920 Int. Cl. H01h 15/06 US. Cl. 20016 9 Claims ABSTRACT OF THEDISCLOSURE An electrical switch having a contactor with either a linearor a rotary movement, a first contact point or plate for supplyingelectrical current to the contactor, a plurality of additional contactpoints or plates positioned for substantially simultaneous engagement bythe contactor, and means elecrically connecting said additional contactpoints or plates together, whereby the additional contact points orplates establish a plurality of parallel circuits with said contactor,all of said circuits being broken upon disengagement of said contactorfrom said additional points or plates, so that the wear and erosion dueto arcing is distributed among said additional points or plates.

This invention relates generally to electrical switches and isapplicable with particular advantage to switches for automotive or othersimilar services.

Many switches basically comprise a supporting member, a contactormovable relative to the supporting member along a pre-determined path, acontact member or other means on the supporting member for supplyingelectrical current to the contactor, and an additional contact member onthe supporting member, positioned for engagement by the contactor, tomake and break the circuit controlled by the switch. The repeated makingand breaking of the circuit causes wear and erosion of the contactor andthe contact member with which it is engageable. Most of the erosion isdue to the arcing which tends to occur when a circuit is broken by thedisengagement of the contactor from the contact member. Eventually, sucherosion may become so extensive as to impair the operation of theswitch.

In accordance with the present invention, the contactor is engageablewith and disengageable from a plurality of additional contact memberswhich may be in the form of points, plates, segments or the like. All ofthe additional contact members are connected together electrically sothat they establish a parallel circuit with the contactor. Thedisengagement or" the contactor with all of the additional contactmembers is substantially simultaneous, so that all of the parallelcircuits .are broken. With this construction, the erosion, due to arcingwhen the circuits are broken, is distributed among the contact members,so that the useful life of the switch is greatly prolonged. It has beenfound that the erosion is self-equalizing. It is virtually impossible toachieve absolutely simultaneous breaking of the circuits. Thus, thearcing occurs at the contact member which is the last to be disengagedby the contactor. Such arcing causes erosion which eventually delays thebreak at this contact member, so that another contact member becomes thelast to be disengaged by the contactor. The arcing then shifts to suchother contact member. In his way, the arcing is shifted to all of thecontact members which are involved in the plural breaks.

It will be recognized that the present invention is particularlyadvantageous for switches which are subjected to a great many cycles ofmaking and breaking circuits. An example of such a switch is the stoplight switch on .an automobile which is cycled whenever the brake pedalis operated. The plural break switches of the present inice vention havegreatly prolonged operating life and thus are especially well suited forsuch services.

Further objects and advantages of the present invention will appear fromthe following description taken with the accompanying drawings, inwhich:

FIGS. 1, 2, and 3 are top, end and side views of a normally closed pushbutton switch to be described as the first illustrative embodiment ofthe present invention.

FIG. 4 is an elevational view of the contact supporting member and thecontacts thereon, taken generally as indicated by the line 44 in FIG. 1.

FIG. 5 is an elevational view of the switch with the contact supportingmember removed, the view being taken generally along the line 55 in FIG.1.

FIG. 6 is a perspective view of the contactor for the switch of FIGS.l-5.

FIG. 7 is a longitudinal section, taken generally along the line 77 inFIG. 3.

FIG. 8 is a transverse section, taken generally along the line 8-8 inFIG. 7.

FIG. 9 is a view similar to FIG. 5, but showing a second embodiment inthe form of a normally open pushbutton switch.

FIG. 10 is an elevational view of the contact supporting member and thecontacts for the switch of FIG. 9.

FIG. 11 is a diagrammatic illustration of the switches of FIGS. 1-10.

FIG. 12 is a diagrammatic illustration showing the extension of theprinciples of the present invention to switches having three or morecontact members which are simultaneously disengageable by the contactor.

FIG. 13 is a diagrammatic view of a rotary switch constituting anotherembodiment of the present invention.

With reference to FIGS. 1-8, the invention will be seen in the form of anormally closed push-button switch 20,

which is suitable for use as the stop light switch of an automobile.Externally, the switch 20 comprises a casing 22, an operatingpush-button 24, and a pair of terminals in the form of lugs or prongs 26and 28. The two wires or leads of the circuit to be controrlled by theswitch are connected to the terminals 26 and 28. When the pushbutton 24is not depressed, the circuit between the terminals 26 and 28 is closedby the switch. Depressing the push-button 24 opens the circuit. Thecasing 22 is shown as being made of metal and rectangular in shape. Amounting bracket 30 is secured to the casing 22.

For automotive stop light service, the switch 20 is positioned so thatthe push-button 24 is depressed by the brake pedal or some other movableelement of the brake system, when the brake pedal is not operated. Thus,the stop light circuit is open. When the brake pedal is operated, thepush-button 24 springs outwardly to close the stop light circuit.

The internal construction of the switch 20 is shown in FIGS. 58. It willbe seen that the switch 20 comprises a contact supporting member 32 andcontactor means, illustrated as comprising a contactor 34- which ismovable relative to the member 32. The movement of the contactor 34 canbe either linear or rotary, but in this case it is linear. Thus, thecontactor 34 is mounted on a carriage 36 which is slidable along alinear path within the casing 22. The push-button 24 is formedintegrally with the carriage 36 and projects outwardly through anopening 38 in an end wall 40 of the casing 22. The carriage 36 is guidedby side walls 42, 44, and 46 of the casing 22.

The carriage 36 is preferably biased to its initial position by a spring48. As shown, the spring 48 is compressed between an end wall 50 of thecasing 22 and an opening or socket 52 in the carriage 36. To insure thatthe contactor 34 will travel with the carriage 36, the contactor isformed with a plurality of tabs or lugs 54 which project laterallytherefrom, and are slidably received in slots or openings 56, formed inthe carriage 36. The illustrated contactor 34 is plate-like in form andis preferably made of sheet metal. The ends of the contactor 34 areshown as being curled or bent to form rounded ramp portions 58. As shownin FIG. 7, the carriage 36 is preferably formed with ribs or ridges 60and 62, with a recess or slot 64 therebetween. The contactor 34 isadapted to be positioned in the recess 64, with the ramps 58 adjacentthe ribs 60 and 62.

The contactor 34 is preferably biased toward the contact supportingmember 32 by a spring 66, illustrated as being compressed between thecontactor and an opening or socket 68 in the carriage 36. The spring 66also biases the carriage 36 against the side wall 46 of the casing 22.

Means are provided to supply electrical current to the contactor 34.Such means are illustrated as comprising a contact point or member 70which is slidably engaged with the contactor 34. The contact member 70may assure various forms but it is illustrated as the sphericallyrounded head of a rivet 72. It will be seen that the rivet 72 extendsthrough a suitable opening in the contact supporting member 32 and isemployed to secure the terminal 26 to the member 32. As shown, thesupporting member 32 is in the form of a plate or board made ofinsulating material. The member 32 closes one side of the casing 22 andis suitably secured thereto.

In accordance with the present invention, the contactor 34 is movableinto substantially simultaneous engagement with a plurality ofadditional contact points or members 74. Two of the contact points 74are employed in the illustrated construction, but three or more could beemployed. The contact points 74 could assume various forms but areillustrated as comprising the spherically rounded heads of rivets 76which extends through suitable openings in the supporting member 32 andare employed to secure the terminal 28 to the supporting member. It willbe seen that the terminal 28 is effective to connect the two contactpoints 74 together electrically. Thus, the contact points 74 establishparallel circuits with the contactor 34.

To provide for smooth operation of the contactor 34, the supportingmember 32 is preferably formed with insulating bosses or points 78 whichare slidably engageable by the contactor, when it is not engaging thecontact points 74. Thus, the illustrated switch has two of theinsulating bosses 78, spaced toward the contact point 70 from thecontact point 74. The insulating bosses 78 preferably take the form ofsemi-perforations, which are punched, molded, or otherwise formed fromthe insulating material of the supporting member 32.

It may be helpful to summarize the operation of the switch 20, as shownin FIGS. 1-8. Initially, the spring 48 biases the carriage 36 to aposition in which the contactor 34 engages the contact points 74, aswell as the contact point 70. Thus, the circuit between the terminals 26and 28 is closed. The contact points 74 establish parallel circuits withthe contactor 34.

When the push-button 24 is pressed, the contactor 34 is moved out ofengagement with both contact points 74, at substantially the same time.Thus, both parallel circuits are broken so that the circuit between theterminals 26 and 28 is opened.

The double break action provided by the two contact points 74 greatlyprolongs the life of the switch because the erosion due to arcing isautomatically distributed between the two contact points, and thecorresponding portions of the contactor 34. This distribution of theerosion is illustrated to best advantage in FIG. 11, in which the erodedareas on the contactor 34 are shown at 80. Although the contactor 34breaks with the contact points 74 at approximately the same time, it isvirtually impossible to provide absolutely simultaneous breaking of thetwo parallel circuits. Thus, at any particular time, the arcing will beconcentrated at the particular contact point 74 which is the last tobreak with the contactor 34.

Eventually, this arcing erodes the contactor 34, the contact points 74,or both, to such an extent that the other contact point 74 will becomethe last to break with the contactor. The arcing then shifts to theother contact point 74. In this way, the arcing alternates back andforth between the two contact points 74. This alternating break actioninsures that the erosion will be distributed between the parallelcontact points.

FIGS. 9 and 10 illustrate a modified switch which is the same as theswitch 20 except that the contact points 70 and 74 are relocated on thesupporting member 32, so that the switch will be normally open. Thus,the spring 48 biases the carriage 36 to an initial position in which}the contactor 34 engages the contact point 70 but not the contact points74. When the push button 24 is depressed, the contactor 34 is moved intoengagement with contact points 74 at substantially the same time. Whenthe pushbutton 24 is released, the contactor 34 breaks with the contactpoints 74 at approximately the same time. However, the break action isnot absolutely simultaneous so that the arcing is concentrated initiallyat one of the contact points 74. After erosion occurs to a sufiicientextent, the arcing shifts to the other contact point 74 so that theerosion due to arcing is equalized. Thus, the provision of the twocontact points 74 virtually doubles the useful life of the switch.

FIG. 11 also illustrated a circuit for either of the switches 20 and 90.As shown, one side of the battery 92 is connected to the terminal 28,and thence to the points 74. The other side of the battery 92 isgrounded. One side of the load 94 is connected to the terminal 26, andthence to the contact points 70, which engages the contactor 34. Theload 94 is shown as a solenoid but may comprise stop lights and otherdevices.

FIG. 12 illustrates an extension of the present invention to a switchhaving three or more of the parallel contact members 74. The contactor34 is adapted to make and break simultaneously with all of the contactmembers 74. Here again, the break action is not absolutely simultaneousso that it actually occurs at one or another of the contact points 74.The resulting erosion due to arcing causes the break action to shiftperiodically to another of the contact points 74, so that the erosion isequalized. The useful life of the switch is generally proportional tothe number of parallel contact points 74 which are pro:

vided.

FIG. 13 illustrates the invention as applied to a rotary switch 120. Inthis case, the switch comprises a contactor 134 which is movable along acircular path. The contactor 134 is mounted on a rotary carriage 136,indicated diagrammatically. The contactor 134 is engageable with astationary contact member and also with a pair of stationary contactmembers 174. The engagement between the contactor 134 and the contactmembers 174 is substantially simultaneous, so that there is a doublemake and break action, as in the case of the previously describedswitches. The contactor 134 is engaged with the contact member 170 whenthe make and break occur between the contactor and the contact members174. Thus, the break action is between the contactor.134 and the contactmembers 174. A terminal member 128 is provided to connect the contactmembers 174 together electrically. Thus, the contact members 174establish parallel circuits with the contactor 134.

In the switch of FIG. 13, the contact members 170 and 174 are plate-likein form and segmental in shape. The contactor 134 is shown as beinggenerally triangular in shape. The illustrated contactor 134 is formedwith a contact point 134a which is engageable with the contact segment170. The contactor 134 also has two other contact points 13419 which areengageable with the contact segments 174.

The areas of erosion are indicated at 180. The break between thecontactor 134 and the contact segments 174 is not absolutelysimultaneous, with the result that the arcing is concentrated at one ofthe contact segments. Eventually, the erosion proceeds to such an extentthat the arcing is shifted to the other contact segment 174. Thus, theerosion due to arcing is automatically distributed.

By virtue of the present invention, the erosion due to arcing can bedistributed so that the effective life of the switch can be greatlyprolonged. This important advantage is achieved with very littleincrease in the size, complexity, or cost of the switch.

Various other modifications, alternative constructions and equivalentsmay be employed, as will be understood by those skilled in the art.

We claim:

1. In an electrical switch,

the combination comprising a casing having one wall providing asupporting insulator,

stationary conductive contact means mounted on the inner side of saidinsulator,

movable conductive contact means disposed in said casing opposite saidstationary conductive contact means,

means for moving said movable contact means in said casing along a pathon said inner side of said insulator and into and out of engagement withsaid stationary contact means,

and terminal means for supplying electrical current to said movablecontact means,

one of said contact means comprising a contact plate having one sidefacing the other contact means,

said other contact means having a plurality of duplicate conductivelyunified contact points located for simultaneous engagement with anddisengagement from different edge portions of said plate on said oneside thereof to distribute the erosion of said contact plate and saidcontact points due to current interruption.

2. The combination of claim 1,

said movable conductive contact means comprising said contact plate,

said stationary conductive contact means comprising said contact points.

3. The combination of claim 1,

said movable conductive contact means comprising said contact points,

said stationary conductive contact means comprising said contact plate.

4. The combination of claim 1, said terminal means comprising astationary contact element slidably engaging said movable conductivecontact means.

5. The combination of claim 1, in which said path of said movableconductive contact means is linear.

6. The combination of claim 1, in which said path of said movableconductive contact means has a circular curvature.

7. In an electrical switch,

the combination comprising a casing,

a plate-like insulator comprising one wall of said casa carriage movablein said casing along a path parallel to the inner side of saidinsulator,

a conductive contactor plate mounted on said carriage and facing saidinner side of said insulator,

a feeder contact point mounted on said insulator and projecting inwardlytherefrom into sliding engagement with said contactor plate to supplyelectrical current thereto,

and a plurality of duplicate conductively unified contact points mountedon said insulator and projecting inwardly therefrom for slidingengagement with said contactor plate,

said duplicate contact points forming duplicate parallel closure pathswhen said contactor plate is engaged with said duplicate contact points,

said duplicate contact points being disposed at corresponding locationsalong the path of said contactor plate so that different edge portionsof said contactor plate are simultaneously disengageable with saidduplicate contact points to distribute the erosion of said contactorplate and said contact points due to current interruption.

8. The combination of claim 7, including a conductive plate on saidinsulator for conductively unifying said duplicate contact points.

9. The combination of claim 7, including spring means between saidcarriage and said contactor plate for biasing said contactor platetoward said contact points and said insulator.

References Cited UNITED STATES PATENTS 1,473,212 11/1923 Davis 200l6XR3,174,000 3/ 1965 Golbeck 20016XR 3,238,318 3/1966 Bleibtreu et al200-10 3,246,101 4/1966 Caputo 200--16XR ROBERT K. SCHAEFER, PrimaryExaminer M. GINSBURG, Assistant Examiner US. Cl. X.R. 200-11,

